Practical applications of hotisostatic Pressing diagrams: Four case studies

Arzt, Eduard; Ashby, Michael F.; Easterling, K. E.

doi:10.1007/bf02651618

Cited by 378 publications

(214 citation statements)

References 9 publications

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“…A method for predicting compaction of granular materials by HIP that has found many applications in modelling technical A60, page 2 of 19 processes was proposed by Arzt et al (1983). An improved version is given in Helle et al (1985).…”

Section: The Basic Assumptionsmentioning

confidence: 99%

“…A collection of such data is presented by e.g. Frost & Ashby (1982) 1 , and Arzt et al (1983). The chondrules and the matrix of the chondritic material are mainly composed of olivine (Mg 2x Fe 2(1−x) SiO 4 ) and pyroxene (Mg x Fe (1−x) SiO 3 ) in varying quantities and varying iron contents, x, and some additional minor components, in particular metallic iron or troilite.…”

Section: Datamentioning

confidence: 99%

“…The kind of approximations used is different in the work of Arzt et al (1983), Helle et al (1985), and in geosciences.…”

Section: Datamentioning

confidence: 99%

“…(7) is related to the shear modulus, μ, the volume diffusion constant, D v , and the Burgers vector, b, via (see e.g. Arzt et al 1983) …”

Section: Approximations As Used In Helle Et Almentioning

confidence: 99%

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Thermal evolution and sintering of chondritic planetesimals

Gail

Henke

Trieloff

2015

A&A

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Context. Reconstruction of the thermal history of individual meteorites which can be assigned to the same parent body allows us to derive general characteristics of the parent body, such as its size and formation time, which hold important clues on the planetary formation process. This requires us to construct a detailed model of the heating of such a body by short lived radioactives, in particular by 26 Al, and its cooling by heat conduction, which may then be compared to the reconstructed cooling histories of the meteorites. Aims. The heat conductivity of the material from which planetesimals are composed depends critically on the porosity of the chondritic material. This changes during the process of compaction (also called sintering) of the material at elevated temperatures and pressures. Therefore, compaction of an initially granular material is a key process determining the thermal history of the parent bodies of meteorites. The most realistic modelling of sintering of chondritic material is required. Methods. The modelling of the compaction process is improved by applying concepts originally developed for the modelling of hot isostatic pressing in metallurgical processes, and by collecting data available from geosciences for the materials of interest. It is extended to a binary mixture of granular components of very different diameters -matrix and chondrules -as observed in chondrites.Results. By comparison with some published data on sintering experiments it is shown that the algorithm to follow the decrease of porosity of granular material during progressive sintering allows a sufficiently accurate modelling of the compaction of silicate material. The dependence of the compaction process on the nature of the precursor material, either matrix-dominated or chondruledominated, is discussed. It is shown that the characteristic temperature at which sintering occurs is different for matrix or chondruledominated precursor material. We apply the new method for calculating compaction to the evolution of the parent body of the H chondrites and determine an improved optimised set of model parameters for this body.

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Section: The Basic Assumptionsmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

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Thermal evolution and sintering of chondritic planetesimals

Gail

Henke

Trieloff

2015

A&A

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“…As is well known, Laves phase can be eliminated through annealing below its incipient temperature. According to Ashby's HIPing diagrams, superalloy powders can be fully compacted within tens of minutes when the HIPing temperature is higher than 1200°C [22]. We realised that the holding time of the HIPing process could be shortened to avoid excessive grain growth during HIPing.…”

Section: Elimination Of Ppbsmentioning

confidence: 99%

Development of Prior Particle Boundary Free Hot-Isostatic-Pressing Process for Inconel 718 Powder

Chang¹,

Yang²,

Sun³

et al. 2014

8th International Symposium on Superalloy 718 and Derivatives (2014)

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Hot isostatic pressed (HIPed) powder metallurgy (PM) Inconel 718 has the potential to be applied in turbine engines. However, the precipitation of high-density carbide particles along the prior particle boundaries (PPBs) leads to its poor ductility and is the main obstacle to be overcome if further and wider applications are pursued. In the past few years, we conducted research aimed at solving this problem, and a HIPing method that could eliminate the PPBs was developed. This paper summarizes the results in three parts: the first is on the influence of HIPing temperature on microstructure and tensile fracture modes of the HIPed alloy; several temperatures ranging from below the Laves incipient temperature to super-solidus were selected. In the second part, typical heat treatments for Inconel 718 were employed for mechanical property optimization of the HIPed alloy. It is found that HIPing at super-solidus temperatures could completely eliminate the PPBs, but the grain size is large and detrimental Laves phase also present. In the third part, a new HIPing process was developed, which consists of a short time holding above the solidus and a long time annealing below the incipient temperature of the Laves phase. This process could produce alloy free of PPBs and Laves phase. After heat treatment, the mechanical properties of the alloy are excellent.

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(De)compaction of porous viscoelastoplastic media: Model formulation

2015

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A nonlinear viscoelastoplastic theory is developed for porous rate-dependent materials filled with a fluid in the presence of gravity. The theory is based on a rigorous thermodynamic formalism suitable for path-dependent and irreversible processes. Incremental evolution equations for porosity, Darcy's flux, and volumetric deformation of the matrix represent the simplest generalization of Biot's equations. Expressions for pore compressibility and effective bulk viscosity are given for idealized cylindrical and spherical pore geometries in an elastic-viscoplastic material with low pore concentration. We show that plastic yielding around pores leads to decompaction weakening and an exponential creep law. Viscous and plastic end-members of our model are consistent with experimentally verified models. In the poroelastic limit, our constitutive equations reproduce the exact Gassmann's relations, Biot's theory, and Terzaghi's effective stress law. The nature of the discrepancy between Biot's model and the True Porous Media theory is clarified. Our model provides a unified and consistent formulation for the elastic, viscous, and plastic cases that have previously been described by separate "end-member" models.

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Practical applications of hotisostatic Pressing diagrams: Four case studies

Cited by 378 publications

References 9 publications

Thermal evolution and sintering of chondritic planetesimals

Thermal evolution and sintering of chondritic planetesimals

Development of Prior Particle Boundary Free Hot-Isostatic-Pressing Process for Inconel 718 Powder

(De)compaction of porous viscoelastoplastic media: Model formulation

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